Answer:
<h3>How did it happen?</h3>
Explanation:
- Cause explains <u>the reason how something has happened or occurred. It helps in finding answers to how an incidence took place</u>. The question one should ask when one sees a cause clue word would be "How did it happen?"
- In this way the cause can be answered with answers explaining how it happened. For instance, when Jim asked Tom "How did it happen?", Tom replied "It happened when I kept the candles close to the screen so that I can do a hand shadow puppet".
<u>Answer:</u>
Eradicating smallpox was successful because of many reasons.
<u>Explanation:</u>
Smallpox was regularly found in an area or we can say it was prevalent in some places. So, mortality rates were high. It was caused by variola virus and affected mainly humans. So, it was essential that such vaccine is developed which can successfully immune people from this disease.
Smallpox vaccine then started spreading across "Europe and North America" and then gradually it spread all over the world and successfully eradicated smallpox by 1980. Other diseases that have been controlled by vaccines are “diphtheria, bacterial influenza, measles, mumps, rubella, and tetanus”.
It would be d. needed a haircut
